1.

Consider the first 10 positve integers .If we multiply each number by -1 and then add 1 to each number,the variance of the number so obtainedA. 8.25B. 6.5C. 3.87D. 2.87

Answer» Correct Answer - A
Since the first 10 positive intergers are 1,2,3,4,5,6,7,8, 9, and 10 on multiplying by-1 we get
-1,-2,-3,-4,-5,-6,-7,-8,-9,-10
On adding 1 in each number ,we get
0 -1,-2,-3,-4,-5,-6,-7,-8,-9
`therefore " " Sigmax_(i)=0-1-2-3-4-5-6-7-8-9`
`=-(9xx10)/2`
= - 45
`Sigma x_(i)^(2)=0^(2)+(-1)^(2)+(-2)^(2)+...+(-9)^(2)`
`- (9xx10xx190)/(6)`
285
`therefore " " SD =sqrt((285)/10-((-45)/10)^(2))=sqrt(285/10-2025/100)`
`=sqrt((2850-2025)/100)=sqrt(8.25)`
Now variance `=(SD)^(2)=(sqrt(8.25)^(2)=8.25`


Discussion

No Comment Found

Related InterviewSolutions